Liquid fuel pumps



Aug.2o, 1963 Y U F.M.EVANS- 3,101,078

LIQUID FUEL PUMPS Filed April 15,1962 v U l Sheets-sheet 1` Aug. 20,1963 EM. EVANSv 3,101,078-

, LIQUID FUEL. P UMPs Filed April 15, 1962 2 sheets-Sheet 2 Fig. 5

United States Patent O 3,101,97 8 LIQUID FUEL PUMPS l Fraser MackieEvans, Uxbridge, Middlesex, England, assigner to C.A.V. Limited, London,England Filed Apr. 13, 1962, Ser. No. 188,616 Claims priority,application Great Britain Apr. 25, 1961 Claims. (Cl. 123-139) Thisinvention relates to liquid fuel pumps for internal combustion engines,and of the kind comprising in combination a rotary distributor adaptedto be driven by the engine, a head at one end of the distributor, saidhead having therein a transversely extending bore, at least one plungerin the bore, means for feeding fuel intermittently as .the distributorrotates to the bore in the head so as to rnove the plunger outwardly, anannular cam surrounding the head and adapted to impart inward movementsto the plunger as the head rotates and thereby deliver fuel through thedistributor to the :engine cylinders in turn, and a liuid operablepiston for imparting angular. movements to the cam to vary the timing ofthe delivery of fuel to the engine.

The object of the present invention is to provide such a pump in animproved form.

According to the invention a pump of the kind specified comprises incombination a cylindrical chamber in which the fluid operable piston isaccommodated, a cylindrical valve member in the chamber, a compressionspring acting between the piston and valve member, a supply passagethrough which fuel at a pressure at least in part dependent upon thespeed of the engine can enter the one end of the chamber to act on thevalve member, a further passage controlled by the valve member wherebythe other end of the chamber can be placed in communication with asource of liquid under pressure ywhen the pressure in the supply passagerises, and whereby said other end of the chamber can be exhausted whenthe pressure in the supply passage falls.

In the accompanying drawings:

i FIGURE l is a sectional side View of a pump incor porating one exampleof the invention,

FIGURE 2 is a part sectional view on the line 2 2 of FIGURE 1,

FIGURE 2a is a fragmentary sectional view of a modication, 'and FIGURE 3is a View similar to FIGURE 2 but showing another niodiication.

Referring iirst to FIGURES l and 2 of the drawings there is provided ahollow body part 4 which lat one end contains a feed pump 5 :of the kindcomprising a rotary impeller provided with varies. The inlet `6 andioutlet (which is connected to the passage 7 in the body part) of thefeed pump are interconnected through a relief valve (not shown) whichregulates the feed pressure in a manner dependent on the speed of thispump. yIn the other end of the hollow body part is contained a fuelinjection pump comprising a rotary head 8 formed on one end of =acylindrical distributor 9 which serves to interconnect the rotary partsof the feed and injection pumps, and which is rotatable in aconventional manner by a multicylindrical internal combustion engine. Inthe head 8 is a transverse bore 10 containing a pair of reciprocatcryplungers 11 which through rollers 12 at their outer ends `co-operatewith a surrounding annular cam 13..

The passage 7 in the body part registers in turn, as the distributor 9rotates, with a plurality of radially disposed passages 14 in thedistributor. The passages 14 are in communication with an axial passage15 in the distributor which opens at one end into the bore 10 in thehead. Also leading from the axial passage 15 is a radial passage 16which is adapted to register inV turn, as the distributor "ice 2rotates, with a plurality of ports 17 in the body part, the ports 17being adapted for connection respectively to the injection nozzles ofthe engine cylinders.

The pump so far described is well known and operates in the followingmanner. Fuel from the feed pump 5 is fed intermittently to the `axialpassage 15 in the distributor and thus serves to move the plungers 11 ofthe injection pump outwardly. At appropriate instants in the cycle theplungers are moved inwardly by the action of the cam d3, and therebyserve to discharge fuel in turn to the engine cylinders through theports 17.

In applying the pre-sent invention to a pump las above described, `astepped cylindrical chamber 18 is formed in the body part 4 adjacent theinjection pump with its axis extending parallel with ra tangent to theannular cam 13, and which has two coaxial parts, :one of the said partsbeing wider than the other. In the wider part of the chamber 18 isslidably mounted a piston 19 which is provided .with a radial gapaccommodating the outer end of a short arm 20 extending radially fromthe annular cam 13, the arrangement lbeing such that axial movement ofthe p-iston will impart angular movement to the cam. In the narrowerpart of the chamber is slidably mounted a cylindrical valve member 21,whilst acting between the valve member and the piston is a `coiledcompression spring 22.

The narrower end of the chamber 18 is connected through a supplypass-age 23 and the passage 7 to the outlet of the feed pump 5 so thatthe pressure at this end of the chamber will be dependent on .enginespeed. More over, the wider end of the chamber is connected through apassage 24 to a port 2S opening into `the wall of the narrower part ofthe chamber, the port 25 being arranged to be covered by the valvemember 21 when the'latter is in an `equilibrium position (as lshown inFIGURE 2).

In the periphery of the valve member is a circumfer- `entially extendinggroove 26 to which fuel from the supply passage 23 can flow by way of `apassage 27 in the valve member incorporating a non-return valve 28..

Assuming that the valve member is in the equilibrium position and thepressure of fuel at the narrower end of the chamber rises, as a resultof an increased speed of the engine driving the rotary distributor 9`and the rotary parts of the Ifeed pump and the injection pump, then thevalve member 21 will be moved towards the piston 19 against the actionof the spring 22. The eect of this is to cause rthe peripheral groove 26in the valve member to register with the port 25, thereby permitting-fuel to ilow yfrom the supply passage 23, to the wider end of thechamber. As a result the piston 19 is moved towards the narrower end ofthe chamber until the pressure on the spring 22 balances the supplypressure and moves the valve member back to the equilibriinn position.During this movement of the piston the annular cam 13 is moved angularlyto advance the instants of injection of fuel through the ports l17.Moreover, during the time the wider end of the `chamber is incommunication with the supply passage 23 the non-return valve 28prevents reverse iiow of iiuid as might otherwise happen as a result ofthe reaction of the annular :cam `13 as it is contacted by the rollersI12. When, on the other hand the pressure in the supply passage Z3falls, the valve member moves towards the narrower end of the chamberthereby placing the wider' end of the chamber in communication with thespace between the piston and the valve member. Fuel can escape from thisspace to the reservoir or the inlet `side of the feed pump through -apassage 29 in the piston 19, a passage 20a in the short arm 20, theinterior of the hollow body part `4l, and a pipe 32 extending `from 1thehollow body part,

anchors It will be understood that the pasasge 27 in the valve member Z1could be replaced by a passage 27 which is provided in the body part asshown in FIGURE 2a, and which incorporates a non-return valve 2b, andlserves to interconnect the narrower end of the chamber with thecircumferentially extending groove 26 in the periphery of the valvemember. l

In the mod-ilication illustrated in FIGURE 3 the passage 27 is omitted,but a further passage 30 is provided as shown in the body part '4, andextends outwardly from one Iside of the narrower part of theV steppedcylindrical chamber 18 at a position intermediate the ends of saidnarrower part. The pasasge 30' incorporates a non-return valve 31 and isintended to be supplied with lubricating oil under pressure from an oilpump 33 drivable by the engine. The operation lof this modification issimilar to that of the rst example described except that lubricating oilis supplied to, yand exhausted from, the 'wider end of the chamber '1Su-nder the control of the valve member 2l when the latter is removedfrom its equilibrium position. rThus, when thevalve member 211 inthenarrower part of the chamber 18 is moved by the pressure `of `fuelsupplied yto the narrower end of the chamber through the supply passage23, as in the first example described, the peripheral groove 26 in thevalve member establishes communication between the passage Si) and theport 25, fand thereby permits the oil pump 33 to supply oil underpressure through the passage 2dto thewider end of the chamber, whereuponthe piston 19is moved towards the narrower end of the chamber. Moreover,when the fuel pressure in the supply passage 23 falls, the valve member21 moves towards the narrower end of the chamber 1S, and communicationis established between the wider end of the chamber and the spacebetween the valve member and the piston 19, whereupon oil can escapefrom this space to an oil reservoir 34 through a passage 29 in thepiston, a passage Zda in the short arm Ztl, the interior of the hollowbody par-t '4, and the pipe 32 extending from the hollow body part, withthe result that the piston moves towards the wider end of the chamberuntil the valve member reassumes its equilibrium position. As shown inFIGURE V3, the inlet of the oil pump It?)` is connected to the lowerpump 533 to the engine bearings, and with one end of a further pipe 39which at its opposite end communicates 'with the upper end of the oilreservoir 34, and which contains a spring-1oaded pressure relief valve46 for enabling some of the oil delivered by the oil pump 33 to bereturned to the oil reservoir when the output pressure of the oil pumpexceeds a predetermined amount.

Havingthus described my invention what I claim as new land desire `tosecure by Letters Patent is:

l. For use in supplying liquid fuel to injection nozzles incommunication respectively with the cylinders of .a multicylinderinternal combustion engine, a liquid -fuel pump comprising incombination a hollow body par-t which is provided with a plurality ofports adapted to be connected respectively to the injection nozzles,acylindrical distributorrotatablyrmounted in said hollow body part, and.adapted to be drivenby the engine, a head rigidly/,united with one endof said distributor, and provided with a transversely extending bore, atleast one plunger slidably mounted in said bore, liquid fuel feed meanswhich is adapted i to be operated by the engine, and from which liquidfuel is intermittently feedable, during rotation of said distributor,through a part the latter to said bore for causing said plunger to moveoutwardly, an annular cam which surrounds said head, and which serves toimpart inward movements to said plunger, during rotation of said headwith said distributor, for delivering fuel through said distributor tosaid ports in turn, a stepped cylindrical charnber which is situatedparallel with a tangent -to said annular cam, and which has two coaxialparts, one of said coaxial parts being wider than the other, `a iluidoperable piston .slidably accommodated in the wider partV of saidchamber, means interconnecting said annular cam and said piston so thatmovement of therlatter causes angular movement of said annular cam tovary the timing of 4the delivery of fuel by said plunger to said ports,a cylindrical valve member -slidably accommodated in the narrower partof said chamber, said narrower part being provided with an outwardlyextending port which is controllable by said valve member, .acompression spring disposed` between, and acting on, said piston andsaid valve member, a supply passage through which fuel from said feedmeans is admissible to lthe narrower end of `said chamber for acting onsaid valve member, .and a second passage which communicates at itsopposite ends respectively with the wider end oi said chamber land theouter end of the last mentioned port, and through which liquid underpressure is admissible to, and discbargeable from, the Wider end lofsaid chamber under the control of said valve member, the -latterhavingassociated therewith a third passage from winch liquid under pressurecan flow through said second passage to the Wider end of said chamberwhen said valve member is moved in one direction by a rise in the liquidlfuel pressure in said supply passage, and said piston being movabletowards the narrower part of said chamber by the liquid under pressureadmitted to the wider end of said said chamber to said supply passage.

chamber, :and having formed therein a fourth passage through whichliquid un-der pressure can iiow from said second passage when said valvemember is returned to its initial position by said compression springfollowing a fall `of the pressure in said supply passage.

2. A liquid fuel pump according to claim l, wherein said third passageestablishes communication between said supply passage `and said secondpassage when said valve member is moved by a rise of the fuel pressurein said supply passage, so thatliquid fuel under pressure iiows fromsaid supply passage through said second passage to the wider end of saidchamber.

. 3. A liquid fuel pump according to claimrZ, and having in associationwith said third passage a non-return valve for preventing return flow offuel from the wider end of 4. A liquid fuel pump according to claim 1,and having in combination therewith fan oil pump which is drivable by.the engine, and from which oil under pressure is admis- 5. A liquid`fuel pump according to claim 4, and having Vin said third passage anon-return valve for preventing return ilow of oil from the wider end ofsaid chamber to ,said oil pump.

References Cited in the tile of this patent UNITED STATES PATENTS2,165,657 Schaeren July 1l, 1939

1. FOR USE IN SUPPLYING LIQUID FUEL TO INJECTION NOZZLES INCOMMUNICATION RESPECTIVELY WITH THE CYLINDERS OF A MULTICYLINDERINTERNAL COMBUSTION ENGINE, A LIQUID FUEL PUMP COMPRISING IN COMBINATIONA HOLLOW BODY PART WHICH IS PROVIDED WITH A PLURALITY OF PORTS ADAPTEDTO BE CONNECTED RESPECTIVELY TO THE INJECTION NOZZLES, A CYLINDRICALDISTRIBUTOR ROTATABLY MOUNTED IN SAID HOLLOW BODY PART, AND ADAPTED TOBE DRIVEN BY THE ENGINE, A HEAD RIGIDLY UNITED WITH ONE END OF SAIDDISTRIBUTOR, AND PROVIDED WITH A TRANSVERSELY EXTENDING BORE, AT LEASTONE PLUNGER SLIDABLY MOUNTED IN SAID BORE, LIQUID FUEL FEED MEANS WHICHIS ADAPTED TO BE OPERATED BY THE ENGINE, AND FROM WHICH LIQUID FUEL ISINTERMITTENTLY FEEDABLE, DURING ROTATION OF SAID DISTRIBUTOR, THROUGH APART THE LATTER TO SAID BORE FOR CAUSING SAID PLUNGER TO MOVE OUTWARDLY,AN ANNULAR CAM WHICH SURROUNDS SAID HEAD, AND WHICH SERVES TO IMPARTINWARD MOVEMENTS TO SAID PLUNGER, DURING ROTATION OF SAID HEAD WITH SAIDDISTRIBUTOR, FOR DELIVERING FUEL THROUGH SAID DISTRIBUTOR TO SAID PORTSIN TURN, A STEPPED CYLINDRICAL CHAMBER WHICH IS SITUATED PARALLEL WITH ATANGENT TO SAID ANNULAR CAM, AND WHICH HAS TWO COAXIAL PARTS, ONE OFSAID COAXIAL PARTS BEING WIDER THAN THE OTHER, A FLUID OPERABLE PISTONSLIDABLY ACCOMMODATED IN THE WIDER PART OF SAID CHAMBER, MEANSINTERCONNECTING SAID ANNULAR CAM AND SAID PISTON SO THAT MOVEMENT OF THELATTER CAUSES ANGULAR MOVEMENT OF SAID ANNULAR CAM TO VARY THE TIMING OFTHE DELIVERY OF FUEL BY SAID PLUNGER TO SAID PORTS, A CYLINDRICAL VALVEMEMBER SLIDABLY ACCOMMODATED IN THE NARROWER PART OF SAID CHAMBER, SAIDNARROWER PART BEING PROVIDED WITH AN OUTWARDLY EXTENDING PORT WHICH ISCONTROLLABLE BY SAID VALVE MEMBER, A COMPRESSION SPRING DISPOSEDBETWEEN, AND ACTING ON, SAID PISTON AND SAID VALVE MEMBER, A SUPPLYPASSAGE THROUGH WHICH FUEL FROM SAID FEED MEANS IS ADMISSIBLE TO THENARROWER END OF SAID CHAMBER FOR ACTING ON SAID VALVE MEMBER, AND ASECOND PASSAGE WHICH COMMUNICATES AT ITS OPPOSITE ENDS RESPECTIVELY WITHTHE WIDER END OF SAID CHAMBER AND THE OUTER END OF THE LAST MENTIONEDPORT, AND THROUGH WHICH LIQUID UNDER PRESSURE IS ADMISSIBLE TO, ANDDISCHARGEABLE FROM, THE WIDER END OF SAID CHAMBER UNDER THE CONTROL OFSAID VALVE MEMBER, THE LATTER HAVING ASSOCIATED THEREWITH A THIRDPASSAGE FROM WHICH LIQUID UNDER PRESSURE CAN FLOW THROUGH SAID SECONDPASSAGE TO THE WIDER END OF SAID CHAMBER WHEN SAID VALVE MEMBER IS MOVEDIN ONE DIRECTION BY A RISE IN THE LIQUID FUEL PRESSURE IN SAID SUPPLYPASSAGE, AND SAID PISTON BEING MOVABLE TOWARDS THE NARROWER PART OF SAIDCHAMBER BY THE LIQUID UNDER PRESSURE ADMITTED TO THE WIDER END OF SAIDCHAMBER, AND HAVING FORMED THEREIN A FOURTH PASSAGE THROUGH WHICH LIQUIDUNDER PRESSURE CAN FLOW FROM SAID SECOND PASSAGE WHEN SAID VALVE MEMBERIS RETURNED TO ITS INITIAL POSITION BY SAID COMPRESSION SPRING FOLLOWINGA FALL OF THE PRESSURE IN SAID SUPPLY PASSAGE.